In a post to Twitter, the tech mogul wrote: "Falcon Heavy remains go for launch at 1.30pm on Tuesday."

Musk later clarified that he meant "Florida time", so Brits will will have to wait until 8.45pm to tune in for the launch.

Falcon Heavy is one of SpaceX's most eagerly awaited launch projects, due to its ability to deliver huge, heavy payloads.

"When Falcon Heavy lifts off in 2018, it will be the most powerful operational rocket in the world by a factor of two," the company explains.

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According to SpaceX, the Falcon Heavy will be able to lift a mass of nearly 64 metric tons – around 141,000lbs – into orbit.

That's heavier than a 737 jetliner loaded with passengers, crew, luggage and fuel.

"Falcon Heavy can lift more than twice the payload of the next closest operational vehicle, the Delta IV Heavy, at one-third the cost," writes SpaceX.

"Its first stage is composed of three Falcon 9 nine-engine cores whose 27 Merlin engines together generate more than 5 million pounds of thrust at liftoff, equal to approximately eighteen 747 aircraft.

Timelapse of the SpaceX Falcon Heavy rocket lifted vertical, as the most powerful operational rocket in the world prepares for first launch

"Only the Saturn V moon rocket, last flown in 1973, delivered more payload to orbit.

"Falcon Heavy was designed from the outset to carry humans into space and restores the possibility of flying missions with crew to the Moon or Mars."

How to watch SpaceX Falcon Heavy launch live online

It's easy enough to watch the Falcon Heavy take-off, because SpaceX live-streams its major launches for free over the web.